Current conventional ignition coil assemblies for internal combustion engines, in particular those for vehicular applications, include a sizeable steel laminated core and associated primary and secondary coil assemblies encased within a fairly thin electrically insulating thermoplastic housing. To mount or permanently fix the coil assembly to the engine or its environs, it is known to provide mounting holes through the core, and sometimes through the surrounding housing also, as is shown in U.S. Pat. No. 4,763,094. This limits the options for placement of the coil assembly within the engine compartment. Specifically, the ignition coil assemblies mentioned above must be mounted on grounded surfaces to eliminate the possibility of electric shock. Further, it has been noted that the differences in thermal expansion coefficients between the housing and laminated core may give rise to stresses in the housing that can affect the waterproof integrity of the assembly and/or lead over time to the propagation of hairline fractures within the housing.
In instances where the core laminations would otherwise be externally exposed, such as in the four tower coil design shown in U.S. Pat. No. 4,763,094, it is also known to provide a soft water-proof layer of insulating tape or like material placed across the inner exposed surfaces of the C-shaped laminated cores. This is an expensive procedure to implement in actual mass production of the ignition coil assemblies. Utilization of the water-proof tape also necessitates adding another operation to the manufacture of the ignition coil assembly on the production assembly line.
The present invention is directed to all the foregoing concerns. Further, the present invention is directed to providing flexibility of manufacturing techniques to allow the same basic coil design to be used for distributor-based and distributorless ignition systems.
Ignition coil assemblies of the prior art are dedicated by design to either distributor or distributorless ignition systems. Distributorless ignition systems typically require high voltage output terminals equal in number to the number of cylinders of the particular engine, for example, a 4-cylinder engine would require a four tower ignition assembly like that disclosed in U.S. Pat. No. 4,763,094. This dedication to a particular ignition assembly design requires respective dedication of the production assembly line machinery to distributor or distributorless production systems.